The present invention relates to a pressure cooker equipped with a device for producing controlled leakage of the sealing gasket.
It is known that, in order to guard against abrupt escape of steam when the user inadvertently opens the pressure cooker without having initially caused a pressure drop within this latter, safety devices are usually provided for producing a controlled steam release as soon as a movement of opening of the pressure cooker is initiated. A safety device of this type also serves to prevent a pressure rise within the pressure cooker if this latter is incorrectly closed.
In particular, in the case of pressure cookers provided with a bayonet closure system, one of the safety devices employed is a push-rod which is mounted on the side of the lid and usually placed within the lid handle. Said push-rod passes through a lateral opening of the lid opposite to one of the bayonet-type lid closure elements and is thrust by restoring means towards the sealing gasket between the lid and the pressure vessel. In the closed position of the pressure cooker, the push-rod is thrust back by one of the vessel closure ramps in opposition to the action of restoring means and the lid-opposition sealing function is fully performed by the gasket. When the lid is incorrectly closed or at the initial moment of opening of the pressure cooker, the push-rod moves away from the closure ramp and exerts an inward thrust on the sealing gasket, thus producing leakage between the sealing gasket and the pressure vessel. The result thereby achieved respectively in these two cases is that a pressure rise within an incorrectly closed pressure cooker is prevented or that the pressure within the pressure cooker is restored to atmospheric pressure before the lid is completely opened.
However, by reason of the manufacturing tolerances of the different components (pressure vessel, lid, sealing gasket and push-rod restoring spring), the leakage thus produced by existing devices is liable to vary to an appreciable extent. The leakage may thus be insufficient, in which case it would cause a pressure rise or else have the effect of maintaining a residual pressure within the pressure cooker. Alternatively, the leakage may be excessive and this would result in a substantial release of steam which would be dangerous for the user at the time of opening of a pressure cooker under pressure.